This application claims the benefit of Korean Application No. 2002-3548, filed Jan. 22, 2002, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method to produce a sintered metal with a high abrasion resistance and durability, and a rotary compressor flange produced by use of the method.
2. Description of the Prior Art
A conventional rotary compressor used to compress coolant of a cooling system includes a stator 2 fixed in a sealed vessel 1 and a driving part 4 having a rotor 3 rotatably set in the stator 2. A compressing part 5 is set in a lower section of the sealed vessel 1 to compress the coolant by a rotating force produced by the driving part 4 (see FIG. 1).
The compressing part 5 includes a rotary shaft 6, which is concentrically combined with the rotor 3, extended to the compressing part 5, and has an eccentric rotor 6a with a predetermined length. A cylinder 7 is set in the compressing part 5 to accept the eccentric rotor 6a of the rotary shaft 6. Two flanges 8 and 9 are mounted to upper and lower ends, respectively, of the cylinder 7, and rotationally support the rotary shaft 6. Furthermore, the compressing part 5 includes a roller 10 rotatably fitted around the eccentric rotor 6a such that the roller 10 rotates and revolves while being in contact with an inner surface of the cylinder 7 when the eccentric rotor 6a is rotated. A vane (not shown) is set in the cylinder 7 and comes into contact with an outer surface of the roller 10. A part above the vane is advanced and retreated in a radial direction of the roller 10 so that an interior of the cylinder 7 is divided into two variable chambers (e.g., a low pressure chamber and a high pressure chamber).
In the conventional rotary compressor, when the eccentric rotor 6a is rotated in the cylinder 7 by a rotating force of the rotor 3, the roller 10 rotates and revolves in contact with the inner surface of the cylinder 7, and the coolant is sucked into the cylinder 7 and compressed while the vane is advanced and retreated in the radial direction of the roller 10. In other words, a low temperature and low pressure coolant flowing into the cylinder 7 through a suction port 12 is compressed and discharged from the cylinder 7 through an outlet port 13 of the upper flange 8.
However, this conventional rotary compressor has disadvantages in that surfaces of the flanges 8 and 9 used for a lengthy period of time are worn because significant friction occurs at contact surfaces between the flanges 8 and 9, the rotary shaft 6, the eccentric rotor 6a, and the roller 10 while the coolant is compressed. Metal powder produced from the flanges 8 and 9 resolves the coolant, and materials produced by resolving of the coolant cause metal parts of the rotary compressor to be eroded and corroded to produce sludge. Consequently, a smooth operation of the rotary compressor is impeded.
Accordingly, it is an object of the present invention to provide a method to produce a sintered metal with an improved abrasion resistance and durability to endure significant friction, and a rotary compressor flange produced by the method.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and other objects of the present invention are achieved by providing a method to produce a sintered metal including kneading metal powder and pressure molding the kneaded powder, sintering the metal powder, subzero treating the sintered metal powder for a predetermined time, and tempering the resulting sintered metal powder under a predetermined compression residual stress.
According to an aspect of the invention, the metal powder includes carbon powder (C) of 0.2 to 0.8 wt %, copper powder (Cu) of 0.5 to 4.0 wt %, nickel powder (Ni) of 1.0 wt % or less, and iron (Fe) powder as a main component.
According to an aspect of the invention, the subzero treating is conducted at xe2x88x92196 to xe2x88x92200xc2x0 C.
According to an aspect of the invention, the subzero treating is conducted for 30 minutes.
According to an aspect of the invention, the tempering step is conducted at 100 to 120xc2x0 C.